Mobile vehicles are typically equipped with rear bumper systems to absorb the force from rear end impacts. Some of the force is transferred from the bumpers to the rails of the underbody in the vehicle. When the rear impact is non-symmetric, the force is unevenly distributed between the sides of the vehicles. Offset loading of the impact force occurs when the impact is not centered on the rear bumper. Symmetric loading of the impact force occurs when the impact is centered on the rear bumper.
The U.S. Pat. No. 4,090,721 impact specifications require the rear portion of a vehicle aft of the end of the rear axle system 110 to crush, which upsets the rear floor and third row seat stability. In the event of a rear impact to the vehicle, the floor in the rear of the vehicle can be crushed pushing the seat structure upward and rearward. If the impact is forceful enough, the door openings of the vehicle can be deformed so that one or more doors cannot be opened normally. Rear impacts can also affect the vehicle fuel system and displace a spare tire stored under the vehicle body.
An apparatus to protect fuel tanks in the event of a rear collision is described in U.S. Pat. No. 4,090,721 of Wedin, et al. Wedin et al. anticipated that their described apparatus, herein called the Wedin apparatus, would satisfy the standards, which were in place in 1976 when the Wedin patent application was filed. The impact test standards have been modified since to 1976 to more rigorous impact tests that the Wedin apparatus would be unable to pass.
Specifically, the Wedin apparatus has no cross-car member to distribute force from a rear impact to both sides of the struck vehicle. The Wedin apparatus does not protect against door opening closure, and it does not stabilize the rear floor of an impacted vehicle. The Wedin apparatus does not provide force distribution of off-center rear impacts.
It is desirable to distribute the force from an off-center rear impact between both sides of the impacted vehicle. It is further desirable to distribute the force from a rear impact on a vehicle along more than one path. It is also desirable to stabilize a rear floor having seat attachments for seating in a second and third row.